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How do the settings on my Gen 5 Samsung ASHP sound?

 
Air Source Heat Pumps (ASHPs)
Last Post by dorkypark 5 months ago
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 cyrusir
(@cyrusir)
Eminent Member Member
Joined: 2 years ago
Posts: 10
Topic starter 14/01/2025 10:35 am  

We have have a 2100 sq feet newish build (8 years ago) which was specced with a samsung Joule system. It has zoned UFH downstairs and the two upper floors have rads. I have really gotten into tinkering with it over the past 2 years especially as i now have power monitoring via a Shelly EM.

At the moment i have my weather comp set at 0 low and 15 high, flow temp at low 38  and 31 at high for both the UFH and the rads. At the moment this seems to be working well at maintaining the temps.

I have opened all downstairs zones so that the UFH is one zone and i have it set to heat to 22.5 overnight (in winter) as we have cheap night rate electricity and decrease to 21.5 during the day with upstairs at 19.5. In the cold snap we maxed out at 34-36 kwh per day (noting that i was artificially pushing this at night with the higher temp but half price unit rate) and in the current mild weather we use around 9 kwh per day (incl DHW which is during the night rate, of the 9 kwh almost 6.5kwh is at the cheap rate with the remaining 2.5 units used during the day to keep the temps as set.)

All look reasonably ok? or anything glaring i am missing?

there isnt much reporting out of the system so i cant get a COP unfortunately.


   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 2 years ago
Posts: 2552
14/01/2025 10:45 am  

Difficult to say without more information about the house however, for comparison, my 200sq m 1930s house with a mish mash of fabric upgrades (including partial, but not full, insulation of the otherwise solid walls) has a measured loss (based on gas consumption) of 7kW at -2.  With my ASHP, consumption peaked at 51kWh during the cold snap and is around 8-10kWh in the more mild weather this year, so  I don't think your figures are a mile out. 

If you are happy with the electricity bills I wouldn't worry.

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 cyrusir
(@cyrusir)
Eminent Member Member
Joined: 2 years ago
Posts: 10
Topic starter 14/01/2025 11:00 am  

@jamespa the house is A3 rated if that helps (per the attached rating sytem we have in ireland)

SEAI.IE "https://www.seai.ie/sites/default/files/ber/understand-a-ber-rating/Sample-BER-Cert.pdf"

 


   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 2 years ago
Posts: 2552
14/01/2025 11:13 am  

Posted by: @cyrusir
↑

@jamespa the house is A3 rated if that helps (per the attached rating sytem we have in ireland)

SEAI.IE "https://www.seai.ie/sites/default/files/ber/understand-a-ber-rating/Sample-BER-Cert.pdf"

 

In that case Id perhaps expect your loss to be less.  Do you have a buffer tank and if so how many ports (usually 2 or 4).  How are the upstairs radiators run and what is the capacity rating and make of your ASHP?

 

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 cyrusir
(@cyrusir)
Eminent Member Member
Joined: 2 years ago
Posts: 10
Topic starter 14/01/2025 11:24 am  

@jamespa ill have to check exactly, pretty sure its an 8kw unit, what would a buffer tank look like? its a Joule system i have if that helps


   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 2 years ago
Posts: 2552
14/01/2025 12:45 pm  

Posted by: @cyrusir
↑

@jamespa ill have to check exactly, pretty sure its an 8kw unit, what would a buffer tank look like? its a Joule system i have if that helps

A buffer tank will be a cylindrical tank other than your DHW tank, or could be attached to your DHW tank.

 

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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Toodles
 Toodles
(@toodles)
Illustrious Member Contributor
Joined: 3 years ago
Posts: 1980
14/01/2025 4:32 pm  

@jamespa Some even sit under the DHW tank rather as though they are a plinth for the tank above. Regards, Toodles.

Toodles, he heats his home with cold draughts and cooks his food with magnets.


   
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 dorkypark
(@dorkypark)
Active Member Member
Joined: 9 months ago
Posts: 9
14/01/2025 9:17 pm  

You can do some ballpark maths to see if it is doing OK.

E.g. if the outside temperature is -2 over a 24 hour period and your flow temperature was 40, then this CoP estimator ( https://heatpumps.co.uk/cop-estimator/) suggests a CoP of 3.04 for a well performing system is possible. Multiply this by your 35 kWh measured electricity consumed to get an estimated heat output of 106 kWh.

106 kWh in 24 hours is an average heat output of 4.42 kW which is about 21 W/m^2. This page ( https://www.heatgeek.com/how-to-size-my-heat-pump-or-boiler-heat-loss-cheat-sheet/) suggests a post-2006 new build should be between 20 and 40 W/m^2 (at around -2), so it's within the expected range (actually on the lower side).

You can fill in your own numbers as needed here but you get the idea...


   
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